This invention relates to a vapor compression system, and specifically to an expander for a heat pump water-heating system.
Typically, a vapor compression system used in a heat pump water-heating system includes an expander for regulating the flow of refrigerant between high-pressure and low-pressure portions of the system. Refrigerant flowing between high and low pressure portions of the vapor compression system releases energy in the isenthalpic or free expansion of the refrigerant. The energy released by the expanding refrigerant is typically lost.
A heat-pump water heating system includes a vapor compression system that heats water within a water circuit. Heated water within the water circuit in turn heats water within a hot water tank. The efficiency of the system is based on the amount of energy input into the system relative to the amount of work provided by the system. Any loss of energy within the system results in an overall reduction in efficiency. Improvement to system efficiency can result in large savings over the operating life of the heat-pump water heating system.
Accordingly, it is desirable to design a system that captures energy released by refrigerant within the expander.